Injection molded product and method for manufacturing same

Abstract

In an injection molded product of the invention, an unevenness forming portion having unevenness formed by thermal expansion of thermally expandable capsules is formed. The injection molded product includes a highly expanded portion that is formed at a surface side of the unevenness forming portion in a thickness direction of the injection molded product and in which the thermally expandable capsules are thermally expanded, and a main body portion that is a portion adjacent to the highly expanded portion in the thickness direction and in which the thermally expandable capsules are substantially not thermally expanded. The thickness of the highly expanded portion is a half or smaller than the thickness of the injection molded product in the unevenness forming portion, and a polymer material of the highly expanded portion and a polymer material of the main body portion are the same polymer material.

The invention claimed is: 
     
       1. An injection molded product that is injection molded from a molding material including a polymer material and a plurality of thermally expandable capsules mixed therein,
 wherein an unevenness forming portion, which has unevenness formed by the thermally expandable capsules after thermal expansion, is formed to only a portion of a design surface formed to a surface of the injection molded product and is visually recognizable when the injection molded product is mounted on a predetermined portion, 
 wherein the injection molded product includes:
 a highly expanded portion that is formed at a surface side of the unevenness forming portion in a thickness direction of the injection molded product and in which the thermally expandable capsules are thermally expanded; and 
 a main body portion that is a portion adjacent to the highly expanded portion in the thickness direction and in which the thermally expandable capsules are substantially not thermally expanded, 
 
 wherein a thickness of the highly expanded portion is a half or smaller than a thickness of the injection molded product in the unevenness forming portion, and 
 wherein a polymer material of the highly expanded portion and a polymer material of the main body portion are the same polymer material. 
 
     
     
       2. The injection molded product according to  claim 1 , wherein the unevenness forming portion includes:
 a first unevenness portion comprising the highly expanded portion formed at a surface side of the first unevenness portion in the thickness direction of the injection molded product and in which the thermally expandable capsules are thermally expanded; and 
 a second unevenness portion comprising an expansion portion formed at a surface side of the second unevenness portion in the thickness direction of the injection molded product and in which the thermally expandable capsules are thermally expanded, the thermal expansion of the thermally expandable capsules in the expansion portion being less than the thermal expansion of the thermally expandable capsules in the highly expanded portion. 
 
     
     
       3. The injection molded product according to  claim 1 ,
 wherein an average particle diameter of the thermally expandable capsules included in the main body portion is smaller than 50 μm, and an average particle diameter of the thermally expandable capsules included in the highly expanded portion is 50  82  m or larger. 
 
     
     
       4. The injection molded product according to  claim 1 ,
 wherein, in the surface of the highly expanded portion, a maximum cross-section height Rt of a roughness curve specified in JIS B0601:2001 is 30 μm or larger and smaller than 200 μm. 
 
     
     
       5. The injection molded product according to  claim 1 ,
 wherein the injection molded product is a vehicle interior equipment that is attachable to the predetermined portion inside a vehicle, and the design surface is exposed to an interior of the vehicle when being mounted on the predetermined portion. 
 
     
     
       6. A method of manufacturing the injection molded product of  claim 1 , the method comprising:
 a filling step of injecting and filling a molding material having the polymer material and the thermally expandable capsules mixed therein into an injection mold formed with a molding cavity having a predetermined shape; 
 a molding step of cooling and solidifying the filled molding material to mold an injection molded body; 
 a taking-out step of taking out the cooled and solidified injection molded body from the injection mold; and 
 a heating step of partially covering the surface of the taken-out injection molded body with a heat shield and heating a portion exposed without being covered with the heat shield, thereby thermally expanding the thermally expandable capsules included in a predetermined portion from the surface of the injection molded body to a thickness of a half or smaller of the thickness of the injection molded body. 
 
     
     
       7. The manufacturing method according to  claim 6 ,
 wherein, in the heating step, after removing the heat shield, by further heating the surface of the injection molded body, degrees of the unevenness of the unevenness forming portion formed to a portion covered in advance with the heat shield and the unevenness forming portion formed to a portion that is not covered with the heat shield are made different from each other. 
 
     
     
       8. The manufacturing method according to  claim 6 ,
 wherein, in the heating step, after the surface of the injection molded body is heated, by partially covering the surface of the injection molded body with a heat shield and further heating the portion that is exposed without being covered with the heat shield, degrees of the unevenness of the unevenness forming portion formed to a portion covered with a heat shield and the unevenness forming portion formed to a portion that is not covered with the heat shield are made different from each other. 
 
     
     
       9. The manufacturing method according to  claim 6 ,
 wherein, in the heating step, the heating of the injection molded body is performed by using radiant heat. 
 
     
     
       10. The manufacturing method according to  claim 9 ,
 wherein the radiant heat is generated by using a near-infrared ray irradiation apparatus. 
 
     
     
       11. An injection molded product that is injection molded from a molding material including a polymer material and a plurality of thermally expandable capsules mixed therein,
 wherein an unevenness forming portion, which has unevenness formed by the thermally expandable capsules after thermal expansion, is formed to only a portion of a surface of the injection molded product and includes:
 a first unevenness portion comprising a highly expanded portion formed at a surface side of the first unevenness portion in a thickness direction of the injection molded product and in which the thermally expandable capsules are thermally expanded; and 
 a second unevenness portion comprising an expansion portion formed at a surface side of the second unevenness portion in the thickness direction of the injection molded product and in which the thermally expandable capsules are thermally expanded, the thermal expansion of the thermally expandable capsules in the expansion portion being less than the thermal expansion of the thermally expandable capsules in the highly expanded portion, 
 
 wherein the injection molded product includes:
 a highly expanded portion that is formed at a surface side of the unevenness forming portion in the thickness direction of the injection molded product and in which the thermally expandable capsules are thermally expanded; and 
 a main body portion that is a portion adjacent to the highly expanded portion in the thickness direction and in which the thermally expandable capsules are substantially not thermally expanded, 
 wherein a thickness of the highly expanded portion is a half or smaller than a thickness of the injection molded product in the unevenness forming portion, and 
 wherein a polymer material of the highly expanded portion and a polymer material of the main body portion are the same polymer material.